Nagpur Division sets national benchmark for Route Relay Interlocking (RRI) signalling system

In 1999, Old Delhi’s stations route relay interlocking (RRI), an advanced signalling system having 1,124 routes entered the record books for being commissioned in 48 hours. After 13 years, Nagpur Central Railway has scripted history by commissioning a RRI system with 533 routes in just two-and-a-half-hours without any hiccups.

RRI is the system used at large and busy stations having large number of train movements. In this, an entire route through the station can be selected and all associated points and signals along the route can be set at once by pressing two buttons for receiving or dispatching trains.

“Conventionally, commissioning of major yards of size comparable to Nagpur takes at least 96 hours with large-scale traffic disruption. Had we followed the old system, at least 600 trains would have been disturbed, but we accomplished the task in which 10% trains were affected,” said divisional railway manager (DRM) Brijesh Dixit.

Reviewing the RRI success after commissioning it a month ago, Dixit told TOI the results were evident. Entry and exit of trains at Nagpur has become safer, smoother and reliable. Now more signalled shunting is possible.

“Now we can manage all the four up and down lines simultaneously for movement of goods train in the yard. Earlier, only two lines could be operated. Secondly, restriction on trains moving to Itwari side have also been removed with the withdrawal of two diamond crossings at Howrah end,” Dixit said.

The commissioning of RRI was done after a lot of brainstorming and meticulous planning. In 2008, Pune RRI with 425 routes was commissioned in 120 hours. In Nagpur, 533 routes were commissioned in 18 hours (yard remodelling in 15.5 hours and actual RRI commissioning in 2.5 hours). Now Dixit is flooded with calls from his counterparts all over India asking how he made it possible.

“It is all team work,” said Dixit modestly. “We adopted a functional approach. It was like keeping a patient conscious while performing an open heart surgery. The life of new system will be 25 years,” he said.

“First, all points, then track circuits and signals were shifted on new cable and patched with old panel during the preparatory stage. This entire exercise was done without causing a single detention,” said Dixit.

Normally, getting Railway Board recognition is tough in railways, but board chairman Vinay Mittal announced an award of Rs 1 lakh for the feat. Besides, Central Railway general manager Subodh Jain announced an award of Rs 5 lakh to all departments involved.

Sudeep Shrivastava, deputy chief signalling and telecommunication engineer (construction), and others involved in project admit that situation in Nagpur was complicated compared to Delhi, Mumbai and Howrah where most of the trains terminate.

“Nagpur yard has most of the trains passing through it and hence any long duration working would have crippled operations in both north-south and east-west directions. We completed the work with bare minimum disruption,” said Shrivastava.

Safer, smoother, reliable

* Operational flexibility enhanced as signalled movements increase from 369 to 533 in new RRI

* At Ajni end there will be more operational options

* Run through facility from Nagpur goods yard to Ajni yard

* Speed restrictions removed near diamond crossing

* Additional route for despatch of trains from platform no. 4, 5 and 6

* Entry and exit of trains has become more safer and smoother